04 GP Shift indicator erratic!

[99z34na]

04 GP GTP.  The DIC screen shows mileage and the shift position.  However the position it reads is going all over between 1 2 3 P D crazy like while driving or sitting.  Also the shift between 1-2 is like getting shoved from behind harsh.  Checked the pcm and what wires I can get at, checked battery and cables, unplugged and replugged DIC.   Going to look at the Neutral Safety Switch and the plug on the Transmission.  
 

never seen anything like this before.   Also it doesn’t always want to start at all.  Like no crank at all.  This is why I’m hoping the Neutral Safety Switch.  
 

any expertise????

[Black92GS]

51 minutes ago, 99z34na said:

04 GP GTP.  The DIC screen shows mileage and the shift position.  However the position it reads is going all over between 1 2 3 P D crazy like while driving or sitting.  Also the shift between 1-2 is like getting shoved from behind harsh.  Checked the pcm and what wires I can get at, checked battery and cables, unplugged and replugged DIC.   Going to look at the Neutral Safety Switch and the plug on the Transmission.  
 

never seen anything like this before.   Also it doesn’t always want to start at all.  Like no crank at all.  This is why I’m hoping the Neutral Safety Switch.  
 

any expertise????

Before you change the range sensor, double check that you don’t have any chafed wiring, corroded pins in the connector etc… first. Don’t want to replace it if there is something else at play. 
 

I can just about guarantee that your no starts and rough shifts are all related, so I wouldn’t worry about those until you get the range sensor issue worked out. 

[55trucker]

You did say that your car is an '04?

The range selector switch/neutral safety switch is internal on an '04 model. It's not mounted to the outside of the case.

[99z34na]

Yes it’s an 04.  And oddly I am not finding the usual YouTube school of fixin’ videos.  Is it a drop the pan kinda job?

 

I’ll be under there next week with some scrutiny and a flashlight.  I got some codes last week that were concerning too.  That’s why I started with the PCM inspection.  

[99z34na]

[99z34na]

These were the codes I got when the shifting became very harsh.  

[55trucker]

That PO742 doesn't sound, if indeed the TCC is locked due to a fault in either the electronic circuitry, the solenoid passage is mechanically gummed up or the clutch is mechanically locked that'll have a severe effect on the engines ability to try to turn over. If in either Park or Neutral & one tries to start the engine if the torque converter isn't releasing the engine will stall near instantly.

In effect the converter is locked up & the converter turbine & impeller will not spin freely of each other. Lock up should only occur in O/D,D & 3rd. 

Yes, one has to pull the trans side cover to get at the range selector. That may mean pulling the trans from the car.

  

Edited 4 hours ago by 55trucker

[99z34na]

2 hours ago, 55trucker said:

That PO742 doesn't sound, if indeed the TCC is locked due to a fault in either the electronic circuitry, the solenoid passage is mechanically gummed up or the clutch is mechanically locked that'll have a severe effect on the engines ability to try to turn over. If in either Park or Neutral & one tries to start the engine if the torque converter isn't releasing the engine will stall near instantly.

In effect the converter is locked up & the converter turbine & impeller will not spin freely of each other. Lock up should only occur in O/D,D & 3rd. 

Yes, one has to pull the trans side cover to get at the range selector. That may mean pulling the trans from the car.

 

2 hours ago, 55trucker said:

  It’s only not started once and it was a no starter situation.  Like nothing, not a click or nothing.  We did hear fuel pump tho.  We wiggled the shifter a bunch and it finally started.  It drives normally until it’s warm.  Then the harsh shifts start.  And the fluctuating drive indicator on the DIC has me thinking it’s still electric and not a mechanical failure.  
 

I sure would like to not drop the transmission since I’ve never done it to a fwd car.  I’ve done the motor mounts and the steering rack twice so I’m familiar with the subframe below somewhat.  

[55trucker]

Let's start here..........what are you using as a scanner?

Is it dedicated OBD2 scanner such as a Matco/Snap-on/OTC?

Is it a laptop with a scanner program loaded onto the laptop?

You want to clear all of those codes, start & run the car in *real time* (the laptop/scanner connected) & drive until those codes reappear.

They're going to be either soft codes or hard codes. Hard codes will not clear until the problem(s) have been solved.

Soft codes usually clear after a number of ignition key/engine run cycles & the PCM corrects.

[99z34na]

My scanner is a WiFi iPhone scanner.  It is mostly read only.  I could dig deeper into its live reading but all I’ve ever monitored was misfires and temps and very simple PIDs.  Unfortunately that level of scanner is the only one in my budget.  I agree live data would be helpful.  
 

Last week after the first check engine light that included p0651 I cleared all codes and forgot about it and hoped it was a fluke (I can dream).  

And then when it started doing the shifting problem I had no CEL and only read codes for the sake of it.  I cleared the second set of codes and hoped it was the heavy rain that day.  (Seriously a big dreamer here) that was the P0742 the first time I believe

the last set of codes was after checking the connections at the PCM and DIC and cleaning up the battery connections for good measure.   There was still no CEL on the dash.  We drove it up the frontage road and back as soon as it shifted hard between 1-2

 

thanks for the ongoing help.   I’ll have much better info when I can get in there more.   Currently not able to work on it due to work.